Field of the Invention
The present invention relates to a laser processing method of dividing a wafer into a plurality of device chips by irradiating the wafer with a laser beam.
Description of the Related Art
Generally, in manufacturing devices, a plurality of chip regions are partitioned by a plurality of streets (planned dividing lines) arranged in a lattice manner on a top surface of a wafer, and devices such as ICs (Integrated Circuits), LSIs (Large Scale Integrations), or the like are formed in these chip regions. Used for dividing these devices is laser processing that forms grooves in the top surface of the wafer by applying a laser beam along the streets of the wafer.
In this kind of laser processing, when the laser beam is applied, minute dust referred to as debris is produced and scattered, and is then deposited on the top surfaces of the devices, consequently decreasing the quality of the devices. A processing method has therefore been proposed which coats the top surface of the wafer with a protective film in advance, then performs laser processing, and cleans and removes debris adhering to the protective film together with the protective film (see Japanese Patent Laid-Open No. 2006-140311, for example). In this kind of processing method, after a liquid resin that is to constitute the protective film is supplied to the top surface of the wafer, the resin is dried by rotating the wafer in a circumferential direction, so that the predetermined protective film is formed.